For driver assistance systems, accurate side vehicle positioning is critical for correct warning. For example, a position of a vehicle in a side blind spot may be detected in real time by a blind spot detection system. When there is a vehicle in the blind spot, if a turn signal lamp is turned on, the system may warn the driver in light, sound, vibration or other forms, so as to ensure drive security. For another example, when a vehicle at either side changes lanes to cut in, the accurate determination by a forward anti-collision system whether the cut-in vehicle occupies a region in front of the vehicle where the system is installed is critical for determining whether to warn or not. Both of the above functions require acquiring a relative position relationship between the vehicles at either side and the vehicle with the system.
In conventional technologies, methods for achieving side vehicle positioning may be roughly grouped into two categories. One category is dual camera method, namely, installing two cameras at the front or the rear of a vehicle, and optical centers of the two cameras are in parallel. A three-dimensional position of a feature point can be calculated from a relationship between positions of the point in two images, so as to achieve side vehicle positioning. However, the method requires high installation accuracy of the two cameras, resulting in a high cost. The other category is single camera method. For example, through a fish-eye camera installed at the front or the rear of a vehicle, a vehicle feature is used to recognize a rough position of other vehicles. The method has a low cost, and low positioning accuracy for other vehicles.